1. Field of the Invention
The invention relates to the technical field of automobile steering mechanisms, and more particularly to a hydraulic steering control valve and a reverse self-locking steering system.
2. Description of the Related Art
An automobile steering system is a special mechanism used for changing or keeping the automobile driving direction, related to the control stability and security of automobiles, and can be divided into two categories: a mechanical steering system and a power steering system. In the mechanical steering system, a manual steering gear is used as a core component, and a steering wheel, a steering shaft, a universal joint, and a link mechanism (a steering tie rod, a steering drag link, etc.) are used as accessories. The power steering system includes a hydraulic power steering system and an electric power steering system. The hydraulic power steering system mainly includes a manual steering gear, a steering oil pump, a steering control valve, and a steering power cylinder; the electric power steering system mainly includes a manual steering gear, a direct-current motor, and a servo mechanism.
To reduce the accidental impact of the road surface to wheels during the automobile driving process as well as the phenomena of kickback of the steering wheel due to the accidental stress to the wheels, the addition of a hydraulic shock-absorbing part (buffer oil cylinder) in the steering mechanism is a commonly used technical means for various steering systems, so that the kickback to the steering wheel under the accidental acting force to the wheels is reduced, and the driving safety performance is enhanced.
The buffer action of the buffer oil cylinder is limited. When a great accidental resistance is applied to the direction guide wheels, the automobile steering mechanism will generate a serious kickback of the steering wheel, and even a driver loses control to the steering wheel. A driver has 0.5 seconds of lag response before being able to control the direction. Thus, the driver fails to restrict the yaw direction due to the accidental resistance to the direction guide wheels, and the driving safety will be seriously affected.
The self-aligning technology is a basic function and technical requirement of a steering system. The self-aligning means that the steering system automatically returns to the straight driving state after the driver eliminates the steering torque and loosens the control to the steering wheel after the steering completion. The steering mechanism automatically turns round (the driver is not required to apply any turning force) under the acting force of the road surface to the direction guide wheels, so that each steering system in the prior art does not have the reverse self-locking function. In the hydraulic power steering system, a valve core of a steering control valve is positioned in the middle (spool in the free state) position when the automobile runs in a straight line or the driver stops steering operation. Oil cylinders on two sides of the steering power cylinder are communicated with a low-pressure oil circuit (oil storage pot) through an oil passage on the valve core, and a piston of the steering power cylinder can freely move, so as to provide a hydraulic passage required for the self-aligning of the steering wheel. In the electric power steering system, a power-driven motor only runs when the steering operation is executed by the driver, and the motor or power-assisted mechanism does not have the self-locking function when the steering operation is terminated, so as to keep the self-aligning function of the steering system.
The conventional steering system has defects due to the lack of a reverse self-locking function. For example, when the direction guide wheels suffer from a sudden accidental resistance, a yaw in direction will be inevitable due to the driver's 0.5 seconds of lag response time to the steering wheel kickback, and the driving safety will be seriously compromised. The realization of a reverse self-locking function of the steering system, prevent and eliminate the kickback to the steering wheel due to the accidental resistance to the direction guide wheels and avoid the yaw in direction due to the external force to the direction guide wheels under the premise of maintaining the self-aligning function of the steering system is a research subject for the technical improvement and upgrading of the steering system.